NCTU LAB 02/04 NUM 4

#include <iostream>
using namespace std;

struct Point{
    int x, y;
}point;

char sign_sin(Point p){
    if(p.y>0){
        return '+';
    }else{
        return '-';
    }
}

char sign_cos(Point p){
    if(p.x>0){
        return '+';
    }else{
        return '-';
    }
}

char sign_tan(Point p){
    if(p.x>0 && p.y>0 || p.x<0 && p.y<0){
        return '+';
    }else{
        return '-';
    }
}

int main(){
    int x, y;
    while(cin >> x >> y){
        if(x==0 || y==0){
            cout << "Invalid point! either x or y located in their axis. Enter a new point : " << endl;
            continue;
        }
        point.x = x;
        point.y = y;
        cout << "sin " << sign_sin(point) << endl;
        cout << "cos " << sign_cos(point) << endl;
        cout << "tan " << sign_tan(point) << endl;
    }
    return 0;
}